The Research On The Effection Of Adhesive Properties Of Potassium Mixing Nano-hydroxyapatite To Zinc Polycarboxylate Cements

Objective: This in vitro study was to observe the contact angle with the previous app-lication of potassium mixing nano-hydroxyapatite, and evaluate the effect ofpotassium mixing nano-hydroxyapatite on the shear strength and microleakage ofZinc polycarboxylate cements(ZPCC).Methods:Used the nano-hydrxyapatite(nHA)、potassium mixing nano-hydroxyapati-te(K-nHA)、Gluma desensitizer(Gluma) individually on the prepared human molarteeth. Observed the change of contact angle on the dentinal surface. Bonded thetitanium metal blocks to the teeth pretreated with nHA、K-nHA、Gluma individuallyand cemented with ZPCC. Measured the shear strength of different groups byuniversal machine. Pure titanium crowns were manufactured for each prepared teethwith the previous application of nHA、 K-nHA、 Gluma and cemented withZPCC,then measured microleakage by sliver-staining method. Analyzed bySPSS17.0statistics software.Results:1. Contact angle experiment:The contact angle on the dentinal surface ofBlank group, nHA group,K-nHA group and Gluma group were35.95±2.77°、20.26±2.44°、11.48±1.94°and27.8±2.62°. The contact angle data of K-nHA groupwere lower than the other three groups and have an statistically difference betweeneach other.2. The result of shear bond strength experiment: The shear bond strength values ofBlank control group, nHA group、K-nHA group、Gluma group were4.438±0.36MPa,4.700±0.50MPa,4.99±0.54MPa,4.636±0.71MPa. The shear bond strength ofthe four groups with ZPCC were not statistically different. The data of fracture modebetween four groups also has no statistical difference.3. Microleakage experiment: K-nHA group lower the data of microleakage value （0.839±0.08mm）and significant differed from the Blank group（0.966±0.09mm）.microleakage of nHA (0.920±0.11mm) drop and Gluma group increased but there isno notable statistic difference with the blank group. The experimental group ofK-nHA showed the less microleakage than the control group of nHA, but notablestatistic difference was found.Conclusion:1、nHA, K-nHA, Gluma desensitizer significantly lower the contactangle of dentin’s surface, increasing the surface energy of dentin, meanwhile K-nHAis a good hydrophilic materials whose contact angle is minimum at dentin surface.2、The ZPCC shear bond strength of nHA、K-nHA、Gluma desensitizer increased indifferent degrees, but not statistically different from the black group. K-nHA crystalsis easier to enter in dentinal tubules and has a better combination with dentin, whichcan improve adhesive strength of ZPCC.3、K-nHA has better sealing function which can significantly reduce micro-leakage.